Currently, the 3GPP (Third Generation Partnership Project) is fostering standardization of LTE-A (LTE-Advanced) as a new mobile communication technology. The LTE-A is an advanced standard of LTE (Long Term Evolution).
According to the specifications of the LTE, a mobile station communicates with one base station. In contrast to this, the following matter is under review with regard to the LTE-A. Namely, a plurality of base stations shares information and communicates with a mobile station in coordination with each other. Such a technique is referred to as coordinated multiple point transmission and reception (hereinafter, also abbreviated as “CoMP”).
As compared with the LTE, the LTE-A is expected to improve a user throughput and a cell throughput at a cell edge (refer to Non-Patent Literature 1). Hence, it has been studied to use the foregoing CoMP for each of a down link (line) and an up link (line).
Non-Patent Literature 2 discloses a method by which a mobile station required even upon utilization of CoMP acquires a peripheral cell list. Moreover, Non-Patent Literature 3 discloses an example of a method for starting CoMP in LTE-A. Furthermore, Non-Patent Literature 4 proposes to carry out only CoMP between sectors in a cell (Intra-eNB) rather than CoMP between cells (Inter-eNB) on starting of the LTE-A. Detailed description of these non-patent literatures will be given later.
It is assumed that network service providers who provide services using a communications standard referred to as the so-called third generation will adopt LTE and LTE-A. As an actual problem, the network service provider will attempt to reduce installation costs by utilizing the current assets as much as possible in order to adopt the LTE/LTE-A as a matter of course. Therefore, it is assumed that an LTE/LTE-A base station is installed in the same place (typically, in the same equipment storage place) as a current base station.
In such a case, when a cell range of the LTE/LTE-A base station is smaller than a cell range of the corresponding existing base station (third generation), services of the LTE/LTE-A cannot be utilized in some regions. For this reason, typically, the cell range of the LTE/LTE-A base station is designed to be equal to or more than that of the existing base station.
The use of a mobile station (User Equipment) capable of utilizing both the service of the existing third generation and the service of the LTE/LTE-A allows a handover between the communications standards.